The round was led by hedge fund sponsor Adage Capital Management with backing from venture capital firms Cycad Group and Nextech Invest, Novartis Venture Fund (NVF), the corporate venturing unit formed by pharmaceutical firm Novartis and Jim Pallotta.

ImaginAb, founded in 2007, has developed technology that reengineers antibodies into smaller proteins that are suitable for diagnostic imagining.

The funding will be used to centralise manufacturing and advance clinical trials for an imaging agent that can determine changes induced in certain types of T-cell tumour infiltrates caused by immuno-oncology treatment, which could help assess if a patient is responding and guide development of other agents.

ImaginAb received $2.3m in seed funding in 2011 from the National Cancer Institute's Small Business Innovation program.

The company added $12.5m in a 2012 series A round featuring NVF, medical holding company Institut Mérieux’s investment vehicle Mérieux Développement, Nextech Invest, Cycad Group and Momentum Biosciences, an investment firm set up by faculty from UCLA and California Institute of Technology.

Mérieux Développement led ImaginAb's $21m series B round in 2014 with participation from NVF, Nextech Invest and Cycad Group.